Low severity · published Sep 29, 2026
CVE-2026-102822
russh: negotiating a MAC-requiring block cipher (CTR/CBC) with mac=none causes a slice-index-out-of-range panic
3.7
CVSS
0.3%
EPSS
No
On KEV
Description
Russh is a Rust SSH client and server library. Prior to 0.63.1, a connection configured to permit mac=none can negotiate it with a MAC-requiring CTR or CBC block cipher because the selection logic validates needs_mac() only when MAC selection fails. A remote peer can then send a packet with a decrypted length of zero, causing russh/src/cipher/mod.rs to shrink the previously read block before indexing buffer.buffer[16..], which panics and terminates the connection task. This issue is fixed in version 0.63.1.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 26% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RU
russh · Eugeny
< 0.63.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-102822
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-102822
x_refsource_CONFIRM
https://github.com/Eugeny/russh/security/advisories/GHSA-p8qx-h547-fjw9
x_refsource_MISC
https://github.com/Eugeny/russh/commit/2885385abfee279092a41d80c6cb6ac367353159
x_refsource_MISC
https://github.com/Eugeny/russh/releases/tag/v0.63.1
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